Crash impact attenuator systems and methods

ABSTRACT

A crash attenuator system for deployment in front of a fixed structure includes a rail extending along a length of the crash attenuator system and a plurality of diaphragms initially disposed in spaced relation along the length of the rail. Each of the plurality of diaphragms moves along the rail, so that when a front end of the crash attenuator system receives an impact force from a vehicle, a first one of the diaphragms moves rearwardly along the rail and impacts a second one of the diaphragms so that both the first and second diaphragms move further rearwardly along the rail, this process continuing with additional ones of the diaphragms until the impact forces have been fully attenuated. A tearing member on the crash attenuator system engages material forming a tearable member of the crash attenuator system, the tearing member tearing material forming the tearable member to increase attenuation of the impact force.

This application is a continuation under 35 U.S.C. 120 of U.S.application Ser. No. 17/071,716, filed on Oct. 15, 2020 and entitledCrash Impact Attenuator Systems and Methods, presently pending, which inturn claims the benefit under 35 U.S.C. 119(e) of the filing date ofU.S. Provisional Application Ser. No. 62/915,592, entitled Crash ImpactAttenuator Systems and Methods, filed on Oct. 15, 2019, and of U.S.Provisional Application Ser. No. 63/054,911, entitled Crash ImpactAttenuator Systems and Methods, filed on Jul. 22, 2020. A1 of theforegoing applications are commonly assigned with the presentapplication, and are each expressly incorporated herein by reference, intheir entirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to crash impact attenuators, andmore particularly to motor vehicle and highway barrier crash impactattenuators comprising fixed systems protecting leading edges ofabutments and other fixed roadside hazards.

Vehicular accidents on the highway are a major worldwide problem and areundoubtedly one of the largest causes of economic and human loss andsuffering inflicted on the developed world today. In an effort toalleviate, in particular, the human toll of these tragic accidents,guardrails, crash cushions, truck-mounted crash attenuators, crashbarrels, and the like have been developed to attenuate the impact of thevehicle with a rigid immovable obstacle, such as a bridge abutment.

A crash attenuator of the type described must absorb the vehicle impactenergy without exceeding limits on the vehicle deceleration. Inaddition, it must accommodate both heavy and light weight vehicles. Thelightest vehicle will set the limit on the maximum force produced by theattenuator and the heavy vehicle—which will experience a lowerdeceleration, and thus will determine the total impact deformationrequired. The force cannot exceed the light vehicle limit and thereforethe initial force and deceleration is low, limiting the energyabsorption. Increasing crash resistance as the vehicle “rides down” fromits impact speed to zero is a vitally important feature of a crashattenuator system which meets rigid governmental safety standards. Thepresent invention accomplishes this objective in an innovative,inexpensive, and very simple, but effective, manner.

The invention, together with additional features and advantages thereof,may best be understood by reference to the following description takenin conjunction with the accompanying illustrative drawing.

SUMMARY OF THE INVENTION

The present invention comprises, in one exemplary aspect, a crashattenuator system for deployment in front of a fixed structure, such asa bridge abutment. The system comprises a rail extending along a lengthof the crash attenuator system, a plurality of diaphragms initiallydisposed in spaced relation along the length of the rail, each of theplurality of diaphragms having a base end adapted to be movably engagedwith the rail, so that when a front end of the crash attenuator systemreceives an impact force from an errant vehicle, a first one of theplurality of diaphragms moves rearwardly along the rail and impacts asecond one of the plurality of diaphragms so that both the first andsecond ones of the plurality of diaphragms move further rearwardly alongthe rail, this process continuing with additional ones of the pluralityof diaphragms until the impact forces have been fully attenuated. Thesystem further comprises a tearing member on the crash attenuator systemwhich is adapted to engage material forming a tearable member of thecrash attenuator system, the tearing member and the tearable memberbeing relatively movable when an impact force strikes the crashattenuator system so that the tearing member tears the tearable member,thereby increasing attenuation of the impact force.

In exemplary embodiments, the tearing member comprises a bolt, and maybe disposed on one of the plurality of diaphragms, such as on a base endof the first one of the plurality of diaphragms. The tearing member maycomprise a plurality of tearing members.

The tearable member extends along at least a portion of the length ofthe crash attenuator and includes a plurality of holes disposed therein,the plurality of holes extending along a length of the tearable memberand spaced lengthwise from one another. The tearing member is engagedwith one of the plurality of holes so that when an impact force isapplied to the crash attenuator, relative motion occurs between thetearable member and the tearing member so that the relative motioncauses the tearing member to tear the material between adjacent ones ofthe plurality of holes, thereby creating a continuous slot, the tearingof the material functioning to attenuate the impact force.

In some embodiments of the invention, the holes are not evenly spacedalong the length of the tearable member having the plurality of holesdisposed therein. For example, adjacent ones of the plurality of holesnearer to one of the front and back ends of the crash attenuator may bemore closely spaced than adjacent ones of the plurality of holes closerto the other of the front and back ends of the crash attenuator. In somecircumstances, the plurality of holes are not uniform in size,respective to one another. For example, in the illustrated embodiment,the frontmost ones of the plurality of holes may be larger and moreelongated than those of the plurality of holes which are located closerto the back end of the crash attenuator, though the directionalorientation may be reversed depending upon application and desiredattenuation characteristics.

In still other variants, the material forming the tearable member may bethinner toward one of the front and back ends of the crash attenuator,and thicker toward the other of the front and back ends of the crashattenuator. In any or all of the embodiments and variants discussedabove, which may be utilized singly or in various combinations, thetearable member may comprise a plurality of stages as it extends fromone of the front and back ends of the crash attenuator toward the otherend of the front and back ends of the crash attenuator, wherein a firststage toward one of the front and back ends of the crash attenuator issofter than a second stage toward the other of the front and back endsof the crash attenuator.

In illustrated embodiments, the one of the front and back ends of thecrash attenuator is the front end of the crash attenuator and the otherof the first and second ends of the crash attenuator is the back end ofthe crash attenuator.

The first stage may be softer because the material forming the firststage is thinner than the material forming the second stage. The firststage may also be softer because the holes of the plurality of holeswhich are disposed in the first stage are closer together than the holesof the plurality of holes which are disposed in the second stage. Thefirst stage may be softer, as well, because the holes of the pluralityof holes which are disposed in the first stage are larger in size thanthe holes of the plurality of holes which are disposed in the secondstage.

In particular embodiments of the present invention, the rail comprisesfirst and second outer rails spaced apart in a widthwise direction, andthe tearable member comprises a center rail. A plurality of fenderpanels are disposed along each side of the crash attenuator along itslength, wherein frontmost ones of the plurality of fender panels areadapted to slide alongside of rearmost ones of the plurality of fenderpanels when the crash attenuator is impacted by a vehicle. A nose box isdisposed at the frontmost end of the crash attenuator. The tearablemember is stationary and the tearing member moves responsive to theimpact force, in particular embodiments, though this may also vary,depending upon design goals.

In still another aspect of the invention, there is provided a crashattenuator system for deployment in front of a fixed structure, thesystem comprising a base portion having a first outer rail extendingalong a length of the base portion, a second outer rail spaced from thefirst outer rail and also extending along a length of the base portion,and a plurality of spaced cross-members extending across a width of thebase portion and joining the first outer rail to the second outer rail.An upper attenuator portion comprises a plurality of diaphragmsinitially disposed in spaced relation along the length of the baseportion. Each of the plurality of diaphragms has a base end adapted tobe movably engaged with each of the first outer rail and the secondouter rail, so that when a front end of the upper attenuator portionreceives an impact force from an errant vehicle, a first one of theplurality of diaphragms moves rearwardly along the first and secondouter rails and impacts a second one of the plurality of diaphragms, sothat both the first and second ones of the plurality of diaphragms movefurther rearwardly along the first and second outer rails, this processcontinuing with additional ones of the plurality of diaphragms until theimpact forces have been fully attenuated. A tearing member is disposedon the upper attenuator portion, which is adapted to engage materialforming a tearable member of the upper attenuator portion, the tearingmember and the tearable member being relatively movable when an impactforce strikes the crash attenuator system so that the tearing membertears the tearable member, thereby increasing attenuation of the impactforce.

In yet another aspect of the invention, there is disclosed a method ofattenuating a crash impact force imposed by an errant vehicle whichwould otherwise strike an immovable object. The method comprises stepsof receiving an impact force at a front end of a crash impact attenuatorhaving a base portion and an upper attenuator portion and causing one ormore members of the upper attenuator portion to move rearwardly alongthe base portion responsive to the impact force. A further step is oneof causing a tearing member disposed on the crash impact attenuator totear tearable material disposed on the crash impact attenuator as theone or more members of the upper attenuator portion move rearwardly,wherein tearing of the material acts to attenuate the impact force.

In certain variants of the method, the tearing member is a projectiondisposed on one of the one or more members of the upper attenuatorportion, which is initially engaged with a hole formed in the tearablematerial. There are a plurality of holes in the tearable material,arranged longitudinally in spaced relation, and the tearing stepcomprises tearing the tearable material between the initially engagedhole and an adjacent one of the plurality of holes, to form a slot. Theone or more members of the upper attenuator portion comprise one or morediaphragms, and the tearable material comprises a rail forming a part ofthe base portion.

The invention, together with additional features and advantages thereof,may best be understood by reference to the following description takenin conjunction with the accompanying illustrative drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an exemplary embodiment of a crashattenuator constructed in accordance with the principles of the presentinvention, disposed in a deployed orientation;

FIG. 2 is an isometric view similar to FIG. 1 , wherein the crashattenuator is in a partially compressed orientation, illustrating thecrash attenuator with an inventive tearing member removed so tearingdoes not occur and the holes or apertures in the center rail arevisible;

FIG. 2 a is an isometric view similar to FIG. 2 wherein the inventivetearing member is present and tearing of the forward apertures 38 hasoccurred to attenuate the impact forces;

FIG. 3 is an isometric view similar to FIGS. 1 and 2 , wherein the crashattenuator is in a fully compressed orientation, but the inventivetearing member has been removed so that tearing does not occur and theholes or apertures in the center rail are visible;

FIG. 3 a is an isometric view similar to FIG. 3 wherein the inventivetearing member is present and tearing of the forward apertures 38 hasoccurred to attenuate the impact forces; and

FIG. 4 is a rearward looking view from the front end of the crashattenuator.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now more particularly to the drawings, FIGS. 1-4 illustrate anexemplary embodiment of a fixed crash impact attenuator system 10 of thetype discussed above, wherein the design is sacrificial, in that it isintended for a single impact only, after which it is replaced. Thus, itis designed to be relatively inexpensive and simple in design andconstruction, yet highly effective in protecting the occupants ofvehicles striking the attenuator.

Design considerations for the system 10 are that it meets U.S. federalTL (Test Level)—3 crash attenuation specifications, that it is narrow inprofile, bi-directional capable, MASH (Manual for Assessing SafetyHardware) compliant, inexpensive, and free-standing (does not need toabut a rigid object, although it can, of course). The system is of asimple design and easy to manufacture (materials are standard sizes andshapes and fender panels are standard Thrie Beam-based), easy toassemble, and ships as a complete assembly. The base is the drilltemplate, and anchor holes can be drilled with the unit 10 assembled.The length of the unit is designed, in an exemplary embodiment, isapproximately 20-24 feet. Its width is 32 inches or less, which permitsthe units 10 to be shipped three-wide on a truck. The height is 32 to 36inches. The unit 10 may be anchored to concrete, asphalt, or a hybrid ofboth, and it is anchored using standard anchors and adhesives. It issuitable for use in temperatures ranging from −40 degrees to 150+degrees F.

In the illustrated exemplary embodiment, the system 10 comprises a baseportion 12 having a ladder frame design, comprising a plurality of crossmembers 14 supporting first and second outer rails 16 and 18,respectively, as well as a center rail 20. The cross members 14 includeanchor holes 22 for anchoring the base to the ground using bolt anchorsor other suitable mechanical fasteners. In some instances, adhesive maybe used instead or as well. The anchor holes 22, in the illustratedembodiment, are spaced along a length of each cross member 14, bothoutside of and within the first and second outer rails 16, 18.

The system 10 further includes an upper attenuator portion 24, whichcomprises a nose box 26, a plurality of diaphragms 28, and a pluralityof fender panels 30. The nose box 26 may comprise a notice sign 32, andmay include a crushable element in the front, behind the sign 32. Thenose box 26 supports loads related to frontal, side, and angled noseimpacts, and is supported on rollers 34, which allow the nose panel tomove rearwardly along the outer rails 16, 18. The rollers 34 aredesigned to prevent binding/locking in an angled nose impact. As thenose box 26 moves rearwardly after a vehicular impact, attenuation maybe activated.

The diaphragms 28 are disposed in spaced relation behind the nose box26. They are made from standard shapes and sizes and have cross bracessized for loads. Each cross brace is positioned for ease of assembly ofthe fender panels 30. Each diaphragm 28 is slidably mounted at theirbase ends 36 on each side to the outer rails 16, 18, as illustrated.

The fender panels 30 are standard in construction, being a standardThrie beam panel, preferably fabricated of 10 or 12-gauge steel. When avehicular impact occurs, and the attenuator is compacted, as shownsuccessively in FIGS. 2, 2 a and 3, 3 a, the fender panels 30 arepreferably designed to nest or double over one another in a slidingpattern, as illustrated in the drawings. The length of the fender panels30 is determined by loads in side impacts, and panels are preferablydesigned to be common and interchangeable where possible. Bolts securethe foremost fender panel 30 to the nose box 26, and also secure thefender panels to the diaphragms 28. The rear of the panels 30 aresecured by clips, rather than slots, in illustrated embodiments, thoughother attachment methods may be used. The system 10 is designed forstandard Thrie beam transition pieces.

The steel forming the fender panels may be galvanized, and may be A36,A513, or A517, for example.

Various approaches for attenuating the crash/impact forces are withinthe scope of the invention. For example, ripper plates may be used, withvaried and staged thicknesses and shapes to stage attenuation,laser/plasma cut patterns to stage attenuation, or a cutter located onthe nose box 26, for example. Shearing bolts may be used, comprisingdouble shear approaches or a cutter on the nose box 26, for example.Failing wire rope sections, comprising wire rope loops being pulled tofailure, kinking of tube arches, cartridges with honeycomb (aluminum,steel, or plastic), crushable foam-filled cartridges, sand-filledcartridges, pea gravel filled cartridges, water-filled cartridges,cartridges filled with glass beads in oil, drawing a metal strip throughoffset rollers, a friction brake on a wire rope, a friction brake on barstock, or velocity magnetics (magnetic attenuation) are all potentialpossibilities.

An attenuation approach which is illustrated in FIGS. 1-4 involves thecenter rail 20. As illustrated, the rail 20 is fixedly mounted to thecross members 14 of the base portion 12, in an upright orientation. Asshown in FIGS. 2 a and 3 a , a plurality of holes or apertures 38 aredisposed in spaced relation along a length of the rail 20.

Attenuation occurs as the upper attenuator portion 24 moves rearwardlyupon impact by a vehicle, thus absorbing impact energy from the crash,and this attenuation capability is greatly enhanced by the employment ofone or more inventive shear bolt or tearing member 40 (FIGS. 2 b, 3 b ,and 4), which extends from the attenuator portion 24, and engages theholes 38. It should be noted, at this point, that FIGS. 2 a, 3 a areillustrated with the tearing member 40 removed, so that the holes 38 areshown, whereas FIGS. 2 b, 3 b show the crash attenuator with the tearingmember 40 in place, as would be the case in an actual installation. Itshould also be noted that the terms “tear”, “rip”, “shear”, “slice”,“cut”, and the like are used interchangeably throughout this applicationto identify any process by which a slit is created in material todissipate and attenuate impact energy. The terms “tear”, “tearing”,“tearable” and the like are used herein and in the appended claims asstand-ins for any of the above mentioned terms for creating a lengthwiseslit in a crash attenuator component to attenuate impact energy, and areintended to be broad enough in scope to include any of these terms.

In the illustrated embodiment, the tearing member 40 is disposed on thefrontmost diaphragm 28, as shown, but it is within the scope of theinvention to employ a plurality of tearing members 40, spaced widthwiseon one diaphragm 28 to tear corresponding structural members like rail20, or opposing sides of the rail 20, or, alternatively, to employ oneor more tearing members 40 on more than one of the plurality ofdiaphragms 28. As shown in FIGS. 2 b, 3 b , as the attenuator portion 24moves rearwardly, the holes 38 are ripped by the tearing member 40, thusabsorbing much of the crash impact forces by ripping the materialforming the rail 20, between the holes 38, creating a slot 42 in therail 20. The holes 38 may be tuned to optimize the tearing, and thusattenuation effect, by changing their spacing in different sections ofthe rail 20, and/or by changing the size of the holes. For example, theholes 38 may be more closely spaced in front portions of the rail 20,and may also be more elongated, to make the rail “softer” when crushed,whereas the holes 38 in more rearward portions of the rail 20 may besmaller and less elongated, and farther spaced apart, in order to makethese portions of the attenuator “harder” when crushed, to attenuatehigher forces. Additionally, if desired, the rail 20 may be made ofthinner material (gauge) in the forward sections, and thicker material(gauge) in the rearward sections, for similar reasons. This adds to the“tuning” of the rail 20. Also, if desired, the material of the railitself might be changed as the attenuator travels along the rail fromfront to rear, from one stage to the next. Of course, though in theillustrated embodiment it is desired that the softer portions be forwardand the harder portions be rearward, differing design considerations maydictate a different orientation, such as softer portions being rearwardand harder portions being forward.

The diaphragms 28 serve to transfer the load of a side impact from thediaphragm to the pavement, through the cross members 14 and anchors 22.This anchoring to the pavement makes the pavement itself a structuralmember for the attenuator system 10.

Thus, important features of the present invention include, for example:

1) low cost;2) free standing (not an end treatment—not relying on the structurebeing shielded for structural support);3) easy assembly—a 20 ft. assembly may be trucked to the site and easilybolted to the ground—standard material lengths make for easier shipping;4) tunability may be altered to adapt to different crash standards andapplications.

Accordingly, although an exemplary embodiment of the invention has beenshown and described, it is to be understood that all the terms usedherein are descriptive rather than limiting, and that many changes,modifications, and substitutions may be made by one having ordinaryskill in the art without departing from the spirit and scope of theinvention.

1. A crash attenuator system for deployment in front of a fixed structure, the system comprising: a rail extending along a length of the crash attenuator system; a plurality of diaphragms initially disposed in spaced relation along the length of the rail, each of the plurality of diaphragms having a base end adapted to be movably engaged with the rail, so that when a front end of the crash attenuator system receives an impact force from an errant vehicle, a first one of the plurality of diaphragms moves rearwardly along the rail and impacts a second one of the plurality of diaphragms so that both the first and second ones of the plurality of diaphragms move further rearwardly along the rail, this process continuing with additional ones of the plurality of diaphragms until the impact forces have been fully attenuated; and a tearing member on the crash attenuator system which is adapted to engage material forming a tearable member of the crash attenuator system, relative motion occurring between the tearing member and the tearable member when an impact force strikes the crash attenuator system so that the tearing member tears the tearable member, thereby increasing attenuation of the impact force, the tearable member being tuned to optimize the tearing of the tearable member, the tearable member being tuned so that portions of the tearable member toward the front end of the crash attenuator system are softer, and thus capable of less force attenuation, than portions of the tearable member toward a back end of the crash attenuator system; wherein the tearable member extends along at least a portion of the length of the crash attenuator and includes a plurality of holes disposed therein, the plurality of holes extending along a length of the tearable member and spaced lengthwise from one another, the tearing member being engaged with one of the plurality of holes so that when an impact force is applied to the crash attenuator, relative motion occurs between the tearable member and the tearing member and causes the tearing member to tear the material between adjacent ones of the plurality of holes, thereby creating a continuous slot, the tearing of the material functioning to attenuate the impact force.
 2. (canceled)
 3. The crash attenuator system as recited in claim 1, wherein the tearing member is disposed on one of the plurality of diaphragms and comprises a bolt.
 4. The crash attenuator system as recited in claim 3, wherein the tearing member is disposed on a base end of the first one of the plurality of diaphragms.
 5. The crash attenuator as recited in claim 1, wherein the tearing member comprises a plurality of tearing members.
 6. (canceled)
 7. The crash attenuator as recited in claim 1, wherein the tearable member is tuned by arranging the plurality of holes so that the plurality of holes are not evenly spaced along the length of the tearable member.
 8. The crash attenuator as recited in claim 7, wherein adjacent ones of the plurality of holes nearer to the front end of the crash attenuator are more closely spaced than adjacent ones of the plurality of holes closer to the back end of the crash attenuator.
 9. The crash attenuator as recited in claim 1, wherein the tearable member is tuned by arranging the holes so that the plurality of holes are not uniform in size, respective to one another.
 10. The crash attenuator as recited in claim 8, wherein ones of the plurality of holes nearer to the front end of the crash attenuator are larger and more elongated than those of the plurality of holes which are located closer to the back end of the crash attenuator.
 11. The crash attenuator as recited in claim 1, wherein the tearable member is tuned so that the material forming the tearable member is thinner toward the front end of the crash attenuator, and thicker toward the back end of the crash attenuator.
 12. The crash attenuator as recited in claim 1, wherein the tearable member is tuned by comprising the tearable member of a plurality of stages as it extends from of the front end of the crash attenuator toward the back end of the crash attenuator, wherein a first stage toward the front end of the crash attenuator is softer than a second stage toward the back end of the crash attenuator.
 13. (canceled)
 14. The crash attenuator as recited in claim 12, wherein the first stage is softer because the material forming the first stage is thinner than the material forming the second stage.
 15. The crash attenuator as recited in claim 12, wherein the first stage is softer because the holes of the plurality of holes which are disposed in the first stage are closer together than the holes of the plurality of holes which are disposed in the second stage.
 16. The crash attenuator as recited in claim 12, wherein the first stage is softer because the holes of the plurality of holes which are disposed in the first stage are larger in size than the holes of the plurality of holes which are disposed in the second stage.
 17. The crash attenuator as recited in claim 1, wherein the rail comprises first and second outer rails spaced apart in a widthwise direction, and the tearable member comprises a center rail.
 18. The crash attenuator as recited in claim 1, and further comprising a plurality of fender panels disposed along each side of the crash attenuator along its length, wherein frontmost ones of the plurality of fender panels are adapted to slide alongside of rearmost ones of the plurality of fender panels when the crash attenuator is impacted by a vehicle.
 19. The crash attenuator as recited in claim 1, and further comprising a nose box disposed at the frontmost end of the crash attenuator.
 20. The crash attenuator as recited in claim 1, wherein the tearable member is stationary and the tearing member moves responsive to the impact force.
 21. (canceled)
 22. A method of attenuating a crash impact force imposed by an errant vehicle which would otherwise strike an immovable object, the method comprising: receiving an impact force at a front end of a crash impact attenuator having a base portion and an upper attenuator portion; causing one or more members of the upper attenuator portion to move rearwardly along the base portion responsive to the impact force; and causing a tearing member disposed on the crash impact attenuator to tear tearable material disposed on the crash impact attenuator as the one or more members of the upper attenuator portion move rearwardly, wherein tearing of the material acts to attenuate the impact force, the tearable material being tuned to optimize the tearing of the tearable member so that portions of the tearable material toward the front end of the crash impact attenuator are softer, and thus capable of less force attenuation, than portions of the tearable member toward a back end of the crash attenuator system.
 23. The method as recited in claim 22, wherein the tearing member is a projection disposed on one of the one or more members of the upper attenuator portion which is initially engaged with a hole formed in the tearable material.
 24. The method as recited in claim 23, wherein there are a plurality of holes in the tearable material, arranged longitudinally in spaced relation, and the tearing step comprises tearing the tearable material between the initially engaged hole and an adjacent one of the plurality of holes, to form a slot.
 25. The method as recited in claim 24, wherein the one or more members of the upper attenuator portion comprise one or more diaphragms, and the tearable material comprises a rail forming a part of the base portion.
 26. The method as recited in claim 24, wherein ones of the plurality of holes nearer to the front end of the crash attenuator are larger and more elongated than those of the plurality of holes which are located closer to the back end of the crash attenuator.
 27. The method as recited in claim 22, wherein the tearable member is tuned so that the material forming the tearable member is thinner toward the front end of the crash attenuator and thicker toward the back end of the crash attenuator.
 28. A crash attenuator system for deployment in front of a fixed structure, the system comprising: a rail extending along a length of the crash attenuator system; a plurality of diaphragms initially disposed in spaced relation along the length of the rail, each of the plurality of diaphragms having a base end adapted to be movably engaged with the rail, so that when a front end of the crash attenuator system receives an impact force from an errant vehicle, a first one of the plurality of diaphragms moves rearwardly along the rail and impacts a second one of the plurality of diaphragms so that both the first and second ones of the plurality of diaphragms move further rearwardly along the rail, this process continuing with additional ones of the plurality of diaphragms until the impact forces have been fully attenuated; and a tearing member on the crash attenuator system which is adapted to engage material forming a tearable member of the crash attenuator system, the tearing member and the tearable member being relatively movable when an impact force strikes the crash attenuator system so that the tearing member tears the tearable member, thereby increasing attenuation of the impact force; the tearable member comprising the rail. 